BBC monthly outlook
Summary
Further wet weather to come, then turning colder
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Saturday 23 November – Sunday 1 December
Somewhat milder for a time with rain, then colder
Over this weekend, Saturday will be the wetter of the two days for many areas, with spells of heavy rain working their way northwards across the country. On Sunday, some places could start foggy, especially in the south. Many places will then have a dry, if fairly cloudy, day. Further rain arriving in the south-west later. For the first half of next week it looks like further bouts of rain will move across from the west, especially for central and southern areas. For many, it will be somewhat milder than of late, especially by night.
From around mid-week onwards, a colder north-easterly wind looks likely to push across the northern half of the UK, and this colder air will then edge southwards for the end of the week and into the weekend. There is some uncertainty over how quickly this will occur though. This brings the threat of some wintry weather in places, especially in the north, and some sharp overnight frosts. There is also a slight chance of rain and snow pushing into some southern areas as fronts encroach here.
Monday 2 December – Sunday 8 December
Cold at first, but likely to turn milder
The signals for a more unsettled, mild and potentially windy spell of weather through early to mid December are still present, although the latest trends in the guidance tend to push this back a little. The start of this week is likely to be rather cold, with further overnight frosts likely, along with a few wintry showers, especially across northern and some eastern areas. The detail on this is quite complex and will need firming on as we get nearer the time via the short to midrange weather forecasts. Through the course of the week, indications are that the colder air will gradually move away to the south-east, with less cold air arriving from the west and north-west, but confidence is quite low on how quickly this transition may occur.
Through Friday 6th and into the weekend, we can expect the north Atlantic jet stream to become active near the UK, pushing areas of low pressure across us once again. This pattern is suggesting milder, but also potentially very wet and windy conditions. Northern and western area seem most exposed to the worst of the wind and rain. This is because a high pressure ridge over France may still be close enough to the south of the UK to deflect some of the fronts away from here and offer some drier interludes.
Monday 9 December – Sunday 22 December
General Election Week is looking mild but also wet
The outlook during the middle of December should be influenced by an active low pressure track across the north Atlantic, passing close to Scotland and then into Scandinavia. During November, the predominant low pressure track has been over southern England or even down over France and Spain. This has prevented the UK from being influenced by the mild south-westerly winds that often accompany our wet weather in winter, so it has been chilly and also wet. The mid-December pattern should be more typical of a UK winter and bring the heaviest rain and strongest winds to northern and western areas, while the southern and eastern half will have some drier interludes between the fronts. Mild on many days.
So for General Election week, and polling day itself on Thursday 12th, the most likely conditions will be mild, with some spells of rain and blustery winds sweeping across the UK. Any colder interludes between the frontal rain bands should be brief, so at the moment the main weather hazards could be related to the wind and rainfall. On the flip side, high pressure over Spain and France will occasionally nudge up into southern areas and bring some calmer and drier days during mid-December.
Looking beyond mid-month and while most indications are for the mainly mild and quite wet and windy pattern to continue, we cannot rule out another cold snap. Wind and temperature patterns high in the Polar Stratosphere (10-20km above the North Pole) are showing signs of significantly changing during December. This can lead to increased forecast uncertainty for a while, but also the chance for colder air to dig back in from the north.
Further ahead
As the holiday season appears on the horizon we'll take an early look at the chances of any colder weather through the Christmas period.
https://www.bbc.co.uk/weather/outlook